Wastewater remediation is a broadly studied art with many innovations. Waste is treated aerobically, anaerobically or both. Inherent in the prior art is accumulation of biomass, called biosolids or sludge. It is costly and difficult to treat biosolids because the contents are virtually unknown and unknowable. Therefore, much of the biosolids are concentrated, digested, composted, land applied or entombed in landfills and the like.
Aerobic systems are well known. They usually involve oxygen-addition, return activated sludge (RAS) as a source of active aerobic bacteria, a mixing step and a clarification step. Some of the clarified solids are returned as RAS or are wasted (WAS).
Anaerobic systems are well known. A common reactor design is the Up-flow Anaerobic Sludge Bed (UASB). Wastewater is pumped into a granular sludge bed to fluidize the granules. Fluid flow allows the gas to escape and the granules return to the fluidized bed. The granules self-form or can be introduced from an outside source.
The biochemistry of biofilms on minerals is well known. A solid mineral is formed (or introduced as a seed crystal). Bacteria colonize the surface. The first colonizers die as they make a sacrificial glue to bond the biofilm to the surface. More colonizers form a synergistic organized collection of bacteria. Bacteria secrete a biopolymer that can bind small mineral crystals to the surface, building up a granule.
Attached growth surfaces are well known. In creeks, for example, slime grows on rocks as flooded aerated water flows by generally in one direction (downhill). In trickling filters, wastewater trickles down over rocks while air is bubbled up from below. Trickling filters are not flooded. An entire ecosystem grows in the thin, aerated film that grazes on the dead and dying attached bacteria. The grazing keeps the trickling filter from fouling.
More recently Kania et al., U.S. Pat. No. 8,372,277 (Kania '277), disclosed a floating streambed of a permeable matrix flooded by flow from a circulator, with or without added air and intended to de-stratify the water column. Kania '277 teaches flow through the permeable matrix. However, a periphyton layer grows over the surface, requiring periodic cleaning.
Circulators are well known (Roberts et al., U.S. Pat. Nos. 8,298,411 and 7,329,351). Impingement aeration to make fine bubbles is also known (Bettle U.S. Pat. No. 5,772,886).
Granules are common in up-flow anaerobic reactors but are not common in ponds as there are no seeds to start the process.